Sunscreen Label Guide: Decoding SPF, PA & Beyond

即使在(zài)紫(zǐ)外綫相對溫(wēn)和的冬季，做(zuò)好(hǎo)防(fáng)曬(shài)依然是(shì)日(rì)常(cháng)護(hù)膚重(zhòng)要的一步。麵對產品(pǐn)上各種專業標識，如何精準(zhǔn)解(jiě)讀(dú)？本文(wén)將(jiāng)幫(bāng)助您(nín)化繁為簡，快速掌握防(fáng)曬(shài)標(biāo)簽的(dí)要點。

While UV radiation may be milder in winter, sun protection remains an essential step in daily skincare. With various technical terms on product labels, how can consumers make informed choices? This guide simplifies key sunscreen labeling information for everyday understanding.

「防(fáng)曬(shài)傷關(guān)鍵：SPF值 / UVB Protection: Understanding SPF」

SPF（Sun Protection Factor）是通用的UVB防護(hù)指數(shù)。UVB是導(dǎo)致皮膚曬紅，曬(shài)傷(shāng)的元(yuán)凶。

SPF (Sun Protection Factor) is the universal metric for UVB protection - the primary cause of sunburn and skin reddening.

1. 定(dìng)義

SPF值基(jī)於“最小紅(hóng)斑(bān)量（MED）"——即(jí)導(dǎo)致皮(pí)膚(fū)剛剛開(kāi)始出現肉眼可見發紅(hóng)（也就(jiù)是(shì)曬紅）所需的(dí)最小紫(zǐ)外(wài)綫(xiàn)劑量(liáng)。

根據(jù)ISO24444的人體(tǐ)測試法(fǎ)，SPF=塗(tú)防曬霜(shuāng)後(hòu)的MED ÷ 未塗防曬(shài)霜的(dí)MED。

簡單(dān)理解(jiě)，SPF值代(dài)表(biǎo)延(yán)長皮(pí)膚被曬傷所需時(shí)間(jiān)的倍數。

1. Definition

SPF is calculated based on Minimal Erythema Dose (MED) - the minimum UV exposure required to cause just-visible skin reddening. According to ISO24444 human testing protocols:

SPF = MED with sunscreen ÷ MED without sunscreen

Essentially, SPF indicates how much longer protected skin can withstand UV exposure before burning compared to unprotected skin.

2. 防護效率(shuài)

SPF值越高，對UVB的阻(zǔ)擋率(shuài)越高，但並(bìng)非(fēi)綫(xiàn)性增長(cháng)。

SPF30 ≈ 可(kě)阻擋97%的UVB

SPF50 ≈ 可(kě)阻擋(dǎng)98%的(dí)UVB

值(zhí)得注意(yì)的是(shì)，SPF值從30提升到(dào)50，阻擋率僅提高了1.3%，但(dàn)產品質地通常(cháng)會(huì)變得更(gēng)厚重。

2. Protection Efficiency

Higher SPF values block more UVB, but not proportionally:

• SPF30 ≈ 97% UVB blockage

• SPF50 ≈ 98% UVB blockage

Note: While SPF50 only provides 1.3% more protection than SPF30, the formulation typically becomes heavier.

3. 常見誤區糾(jiū)正(zhèng)

• 錯(cuò)誤(wù)觀念(niàn)：SPF值能直接(jiē)換算成(chéng)固定的“安全保(bǎo)護時(shí)長"。

• 正確觀念：防曬效(xiào)果(guǒ)會因(yīn)使(shǐ)用(yòng)量，環境(jìng)因(yīn)素(sù)等動態變(biàn)化(huà)，所以SPF值(zhí)代表的(dí)是對紫外綫(xiàn)劑量的(dí)阻擋(dǎng)能力，而非一(yī)個(gè)固(gù)定(dìng)的時間(jiān)承(chéng)諾(nuò)。如果塗抹量不(bù)足(zú)，即使使用SPF50的(dí)產品，實(shí)際(jì)防(fáng)護(hù)效果也會(huì)大(dà)打折扣(kòu)，可(kě)能(néng)降至SPF10左右(yòu)。

3. Common Misconceptions

• Myth: SPF directly converts to guaranteed "safe sun exposure time"

• Fact: SPF indicates UV dose blockage capacity, not fixed time protection. Real-world factors like application amount and environmental conditions significantly impact effectiveness. Insufficient application (less than 2mg/cm²) can reduce SPF50 performance to SPF10 levels.

「防曬(shài)黑/防(fáng)曬老關(guān)鍵：UVA防護(hù) / UVA Protection: Preventing Tanning & Aging」

UVA是導(dǎo)致(zhì)皮(pí)膚(fū)曬(shài)黑(hēi)，老化和產生皺(zhòu)紋(wén)的主(zhǔ)要(yào)因素。目前(qián)每個(gè)地區(qū)對UVA的(dí)防護(hù)標準(zhǔn)尚未統(tǒng)一，主要(yào)有以下(xià)三(sān)種體係：

UVA causes skin darkening, aging and wrinkles. Global UVA protection standards vary:

1. 中(zhōng)日韓標準：PA指數(shù)

PA等(děng)級(jí)基(jī)於PFA值(zhí)（防護(hù)UVA指數），看皮(pí)膚要(yào)多大的紫(zǐ)外綫量才會開始(shǐ)被(bèi)曬黑(hēi)。用“+"號表示防護強(qiáng)度：

PA+：PFA 2-3，輕度防護效(xiào)果(guǒ)

PA++：PFA 4-7，中度(dù)防護(hù)效果(guǒ)

PA+++：PFA 8-15，高(gāo)度防護效果(guǒ)

PA++++：PFA≥16，超高度(dù)防(fáng)護效果

“+"號越多(duō)，越(yuè)不容易(yì)曬黑，防護UVA的(dí)能力越強。

1. Asian Standard: PA Rating

PA grades based on Protection Factor of UVA (PFA) - measuring UV dose required to induce tanning:

• PA+: PFA 2-3 (basic protection)

• PA++: PFA 4-7 (moderate protection)

• PA+++: PFA 8-15 (high protection)

• PA++++: PFA≥16 (very high protection)

More "+" symbols indicate stronger UVA protection. China's highest rating is PA++++.

2. 美(měi)國標準：廣譜(pǔ)防曬（Broad Spectrum）

美國(guó)不(bù)采用(yòng)PA值，而(ér)是采用(yòng)“廣(guǎng)譜防曬(shài)"標準。產(chǎn)品(pǐn)必(bì)須(xū)同時(shí)滿足：

• SPF值≥15

•臨(lín)界波長（CW）≥370納(nà)米(mǐ)

達(dá)標的產品(pǐn)可(kě)標注“Broad Spectrum"。未(wèi)達(dá)標的產(chǎn)品則需在標簽上注明警(jǐng)示語，提(tí)示(shì)該(gāi)產品僅(jǐn)能防曬(shài)傷(shāng)，不(bù)能預(yù)防(fáng)皮膚癌或(huò)皮(pí)膚老化。

注：臨(lín)界(jiè)波長（CW）：由(yóu)美國皮膚(fū)科(kē)醫學會提(tí)出(chū)。指(zhǐ)防(fáng)曬產品經(jīng)過(guò)測(cè)試(shì)後能(néng)阻(zǔ)斷(duàn)90%紫外(wài)綫(xiàn)的zui大波(bō)長，簡(jiǎn)單來說，CW數(shù)值越(yuè)高，能夠(gòu)防(fáng)護的波長範圍越(yuè)廣，對紫外綫的(dí)防(fáng)護(hù)效果(guǒ)越好。

2. US Standard: Broad Spectrum

Requirements:

• SPF≥15

• Critical wavelength (CW)≥370nm

Products meeting both criteria can claim "Broad Spectrum." Others must warn they only prevent sunburn, not skin cancer or aging.

Critical wavelength (CW): The longest wavelength blocking 90% of UV. Higher CW values indicate broader UV protection spectrum.

3. 歐(ōu)洲標準(zhǔn)：UVA圓(yuán)圈與(yǔ)Boots星級

• UVA圓圈：如果產品包裝(zhuāng)上有一個(gè)UVA字母(mǔ)外(wài)麵(miàn)畫著(zhuó)圓圈，代(dài)表其臨界波(bō)長(cháng)≥370納(nà)米，且UVA防(fáng)護力至(zhì)少達到(dào)SPF值的(dí)三(sān)分(fēn)之(zhī)一(yī)。

• Boots星(xīng)級：用星級(jí)（一(yī)至五(wǔ)星）來標示UVA與UVB防護能力的均衡(héng)度。星級越(yuè)高，當兩(liǎng)者(zhě)防護越均(jūn)衡(héng)，越能同時防護(hù)UVA和UVB，能(néng)更全(quán)麵抵(dǐ)抗紫外對皮膚的(dí)傷害。zui多(duō)為五(wǔ)星(xīng)。

3. European Standard: UVA Circle & Boots Star Rating

• UVA Circle: Indicates CW≥370nm and UVA protection ≥1/3 of SPF value

• Boots Stars (1-5): Rates UVA/UVB protection balance. Higher stars mean more balanced protection against both UV types.

「防水防(fáng)汗功能 / Water Resistance Claims」

1. 中國標(biāo)準(zhǔn)

• 抗水抗汗：產品通過(guò)40分鐘(zhōng)的(dí)測試，可標注(zhù)“防水防汗"，需注明(míng)時(shí)間(jiān)不(bù)超(chāo)過40分鐘。

• you yue抗水：產品通(tōng)過80分(fēn)鐘的測試(shì)，可(kě)標(biāo)注(zhù)“you yue抗水"，需注(zhù)明時(shí)間不超(chāo)過80分鐘(zhōng)。

• 若(ruò)浸泡後(hòu)SPF值下降超(chāo)過50%，則(zé)不(bù)得宣(xuān)稱具有防水功(gōng)能(néng)。

2. 美(měi)國標(biāo)注(zhù)

一(yī)般標(biāo)注(zhù)為“Water Resistant"。

1. China Standards

• Water Resistant: Maintains SPF after 40min water immersion

• Very Water Resistant: Maintains SPF after 80min

Products losing >50% SPF after testing cannot claim water resistance.

2. US Standards

Labeled as "Water Resistant "

「其(qí)他(tā)標(biāo)識 / Additional Label Terms」

• Safe-Eye Tech：產(chǎn)品通過(guò)驗證測(cè)試，可在(zài)眼周使(shǐ)用(yòng)，不易熏眼。

• Wet Skin：可(kě)在(zài)濕皮膚(fū)上直接塗(tú)抹(mǒ)，非常適合海(hǎi)邊(biān)，泳池等場(cháng)景。

• 12M：建(jiàn)議(yì)開(kāi)封(fēng)後12個月(yuè)內用完(wán)。防(fáng)曬劑穩(wěn)定(dìng)性會(huì)隨(suí)時間(jiān)下(xià)降(jiàng)，隔(gé)年的(dí)防曬霜防(fáng)護效果會大打(dǎ)折扣(kòu)，不建議繼(jì)續(xù)使用。

• Safe-Eye Tech: Ophthalmologist-tested for eye area use

• Wet Skin Application: Can apply to damp skin

• 12M: Use within 12 months after opening for optimal efficacy

說到底，防曬可不(bù)是(shì)簡(jiǎn)單(dān)買個指數好的(dí)產品就(jiù)萬事(shì)大吉(jí)了。真(zhēn)正的秘訣(jué)在(zài)於“塗夠(gòu)量，勤(qín)補塗"，再(zài)搭(dā)配上帽子，墨(mò)鏡這些(xiē)硬(yìng)防曬裝(zhuāng)備，才能做到(dào)有效的防(fáng)曬。

記住(zhù)這個(gè)挑選小(xiǎo)竅門(mén)：

日(rì)常上(shàng)班(bān)通勤：選擇(zé)質地(dì)輕薄，不(bù)粘膩的(dí)，方便隨時補塗。

戶外運動，海(hǎi)邊玩水(shuǐ)：防水防汗功(gōng)能(néng)是(shì)重中之重(zhòng)，一(yī)定要認(rèn)準(zhǔn)明確的抗(kàng)水標識(shí)。

Ultimately, sun protection isn’t as simple as buying the product with the highest SPF and calling it a day. The real secret lies in applying a sufficient amount and reapplying it frequently, combined with physical protection like hats and sunglasses, to ensure complete safety.

Keep this selection tip in mind:

For daily commutes: Choose lightweight, non-sticky formulas for easy reapplication.

For outdoor activities or beach trips: Water and sweat resistance is crucial—always look for clear waterproof labeling.